Polarized alternating current ringer or buzzer for telephone subsets and similar apparatus



May 11, 1954 R. COMPARE 2,678,436 POLARIZED ALTERNATING CURRENT RINGER oR BUZZER FOR TELEPHONE SUBSETS AND SIMILAR APPARATUS Filed Feb. 19, 1952 2 Sheets-Sheet l F/GZZ. 2

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I/VVENTOR I I /e /s R.COMPARE ATTORNE Y I May 11, 1954 R COMPARE 2,678,436

' POLARIZED ALTERNAT ING CURRENT RINGER OR BUZZER FOR TELEPHONE SUBSETS AND SIMILAR APPARATUS Filed Feb. 19, 1952 2 Sheets-Sheet 2 F/GS.

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' J B 95 & 29 i INVENTOR R.COM'PARE ATTORNEY Patented May 11, 1954 POLARIZED ALTERNATING CURRENT RINGER OR BUZZER FOR TELE- PHONE SUBSETS AND SIMILAR AP- PARATUS Renato Gompa're, Milan, Italy, assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application Feb'ruary19, 1952, Serial No. 272,479

Claims priority, application Italy February 21, 1951 Claims. l

The invention relates to an improvement in electric signalling devices, and particularly to: signalling devices actuated from a source of alternating current, useful particularly in the ringers of telephone sub sets.

The prior art devices were relatively bulky in size and required considerable operating power input by reason of their size. My invention provides a compact structure which permits operation: with a minimum power input rendering the signal device highly sensitive and economioal in operation.

One of the features of the invention resides in an alternating current ringer or buzzer comprising a current magnet, a gong of magnetic material, an induction coil with its associated plunger movably mounted within the coil for free displacement at the frequency of the alternating current'source under the control of the variable magnetic field produced between the fixed field of the permanent magnet and the variable field induced in said coil from the alternating current flowing therethrou'gh from the source.

Another feature of the invention resides in an alternating current ringer provided with an induction coil wound around a hollow tube of magnetic material, through which a. plunger is free to. move in two axial directions, whereby one orboth. the ends of said'plunger can alternatively strike the edges of the gong with a rhythm in accordance with the alternating current frequency applied. to said coil, said coil, said tube and said: plunger tobe mounted within said gong.

A further feature .ofthe invention resides in a ringer or buzzer in which there is utilized a combination between a fixed magnetic field, provided-by a permanent magnet, situated in operative relationship with an induction coil and a variable field generated by the induction coil when an alternating, current is flowing therein.

Aiurther feature. of the invention resides in a ringer of which the gong forms part of the permanentmagnetic' circuit, the magnetic circuit being. alternatively closed by a mobile plunger similarly made of magnetic material, the plunger being kept ina state of magnetic equilibrium when no alternating current is applied to the inductioncoil.

The above and other objects and features of the invention will become more apparent and the: invention itself will; be best understood by reference to the following description of various embodiments" thereof, taken in conjunction with the accompanying drawing in which:

Figure 1 is' a sectional view of. a first em'bodiment of the invention;

Figure 2 is a schematic diagram of the-distribution of the permanent magnetic field existing among the several members of the device;

Figure 3 is a view partly in section of the ringer of Fig. l with a modified form of plunger;

Figure 3A is an end view of an end washer showing the detail of a mounting of the resetting spring;

Figure 4 is a bottom view partly in section of another modified form of the structure of Fig. 1;

Figure 4A is a view partly in section ofv the plunger elements which co-operate with the embodiment shown in Fig. 4;

Figure 4B is a profile view of a spring clamp used to combine the elements of Figs. 4 and 4A;

Figure 5 is a bottom view partly section. of

another modified form of the structure of Fig. 1; and

Figure 6 is a bottom view partly in section of another modified form of the structure of Fig. 1.

Referring now to Fig. l, which is a first. embodiment of my polarised alternating current ringer, I provide the gong I made of magnetic material, a permanent magnet-2,. and a magnetic extension member 3 extending perpendicular to the magnet. A screw 5 of magnetic material extends through the center 5 of the gong from the outside of the crown through to support within the hollow interior of the gong, the permanent magnet tube and the magnetic extension member 3. The magnet is provided with a hole- 6 which is of sufiicient diameter topass the screw l, and the extension member '3 is provided with a threaded hole I to accommodate the screw 4. Extending through the extension member 3- and perpendicular thereof, I provide a solenoid which comprises a hollow magnetic coil form 8 having end washers 9, on opposite ends thereof, which washers are of insulating material. The coil form is wound with a predeterminednumber of turns of insulated wire Ill and the winding about the form will be seen to be in two separate sections [0A and 10B, one section IDA being placed on one side of the member 3 and the: other section being placed on the opposite side. of the member 3. The outer ends of the coils are fixed in a suitable fashion such" as by solder-- ingto the terminal lugs I'I,-andthe inner ends of the coils are electrically connected together. (Jo-operating with the coils and the coil form I provide a plunger or striker rod l2 which is also made of magnetic material and which is adapted to freely move axially alongthe center of the hollow coil form. The ends of the plunger I2- are provided with bluntly shaped heads l3 and which heads may be covered by non-magw netic material to prevent magnetic attachment to the gong I.

Figure 2 will aid in the explanation of the working principle of my invention. It will be seen that by poling the permanent magnet as shown on the drawing the entire gong assumes a magnetic polarity, in the example shown a north magnetic polarity. The device would operate equally as effective if the permanent magnet were reversed and a south polarity were applied to the gong. In the example shown however, the south polarity is conducted through the extension member 3 through the hollow magnetic coil form 8 to the ends of the plunger I2, as shown in the drawing. As shown in Fig. 2, the plunger is in a state of magnetic equilibrium, the polarity of both ends being identical so that the pull between the right hand end of the plunger toward the gong is equal to the pull of the left hand end of the plunger toward the gong. Upon application of alternating current to the winding III however, the ends of :the plunger are alternately made positive and negative in accordance with the alternations of the current. Thus, at a given instant the right hand end of the plunger would be magnetized to assume a north polarity and at the same instant the opposite end of the plunger would be more strongly magnetized to be given a stronger south polarity. Therefore, the gong would repel the north polarity on the right side of the plunger and would attract the left side of the plunger causing the plunger to move laterally toward the left and into contact with the gong I. Upon reversal of thealternating current polarity the plunger will move toward the right, the magnetic conditions now being reversed.

As the plunger strikes the gong audible sound, of course, is produced. It will be understood that ,the oscillations of the plunger will depend upon the frequency of the alternating current applied to the winding. This novel construction permits sufiicient operation with a minimum motivating power required; a sample ringer having required but 0.06 watt of input power for operation. This makes for a structure of high sensitivity and economical operation due to the low power requirements.

The first modified form of the structure of Figs. 1 and 2 is shown in Fig. 3 which has a bottom view partly in section of the 1 structure. The difference in the Fig. 3 structure over that of Fig. 1 resides in the plunger which co-operates with the electromagnet and which has been designated by reference numeral IS. The plunger I3 is provided with a pair of circular grooves extending an equal distance from the ends of the plunger and which constitute raceways for ball bearings I4 which serve to carry the plunger !3 against the wall I5 of the hollow core 8. The plunger is of any suitable cross section but preferably cylindrical. In this embodiment I further provide two diametric slots I6, each made near the end of the plunger and each adapted to receive the end of a thin U-shaped spring I1, which extends over the washers 9. An end view of the manner in which the spring I'I co-operates in the slots I8 may be seen in Fig. 3A. The structure shown in Figs. 3 and 3A operates against the tension of each of the arms of the spring I "I alternately, the spring serving to return the plunger to normal position upon the arrival to a zero voltage condition of the alternating current between cycles.

In Fig. 4 I show another embodiment of my invention, the modification over Fig. 1 again lying in the plunger arrangement. In Fig. 4 I provide a hollow coil form of magnetic material I8 having the end washers I9 spaced from the ends of the form I8 as shown in the drawing. At one end of the coil form I8, I provide two slots 28 and 2|, these slots being diametrically opposite and parallel to each other. Adapted to fit within the hollow portion of the form I8 I provide a hollow magnetic sleeve 22 shown in Fig. 4A. Element 22 ,has a length slightly greater than that of the length of the inside of coil form I8 and is of a diameter slightly smaller than the inside diameter of the form I8. Thus, the element 22 may freely move longitudinally within the coil form I8. At one end of the element 22 I provide a pair of slots 23 and 24 which slots are diametrically opposite each other and parallel as shown in Fig. 4A. There is further provided a non-magnetic plunger element 25 which has a diameter slightly less than that of the inside diameter of the element 22. The plunger 25 is provided with a circular groove 26 near one end thereof having a width equal to the distance that the plunger must travel when it is placed within element 22, which element is in turn placed within the coil form I8 of Fig. 4.

As shown in Fig. 43, I provide a spring clamp having a generally U-shaped profile and which is adapted to clamp into groove 28 in element 25, groove 24 in element 22, and is adapted to further remain within the slots 28 and 2| cut into coil form I8 of Fig. 4. Thus, upon energisation of the electromagnetic coil by magnetic current, which coil would be wound around coil form I8 in a fashion similar to that in Fig. 1, the element 22 being of magnetic material will tend to respond to the alternations in magnetic polarity but its travel will be limited by the width of the slots 28 and 2I in the coil form I8 by reason of the element 21. By the same token, the non-magnetic plunger 25 will tend to continue to move in the direction of movement taken by element 22, due to the loss of momentum, but its travel in turn, will be limited by the width of the slot 28; thesides of the slot 26 abutting against the element 21 and the length of travel thereof being limited by the width of the slot as above stated. By utilising the plunger of non-magnetic material no problem of magnetic adhesion with the magnetised gong could possibly arise. During operation of the embodiment shown in Figs. 4, 4A and 43 it will be understood that the element 22 will move longitudinally within the hollow coil form I8 in accordance with the frequency of the alternating current flowing in the coil winding and the motion will be imparted to the plunger 25, the motion occurring in both directions.

Still another embodiment is shown in Fig. 5, which is a bottom view partly in section of another modified form of the section of Fig. 1, the modification being in the placement of a pair of resilient arms 28 to the ends of a plunger 29."

At the free ends of the arms 28 I provide a weight 38, which acts as a clapper against the sides of the gong I alternately upon the excursion of the plunger 29. The ends of the plunger 29 are provided with suitable stops 3| to limit the movement of the plunger in either direction through the hollow coil form.

In Fig. 6 a still further embodiment is provided. Fig. 6 is a bottom View partly in section of another modified form of the structure of Fig. l, the plunger 32 being similar to the plunger I2 of Fig. 1, with the exception that a pair of slots 33 are provided in either end of the plunger 32 within which slots a pair of non-magnetic rods 34 are adapted to freely move in an axial direction of the plunger, their degree of travel being limited, of course, by the ends of the gong I. It will be understood that with the oscillating movement of the plunger 32, the rods 34 will be alternately projected toward the gong partially out of the slots 33 but will be returned within the slots by reaction against the side of the gong. By means of this embodiment any possible magnetic adhesion of the plunger to the gong is avoided.

It is within the purview of this invention to also provide a non-metallic gong (not shown) the only requirement to be followed being the provision of a magnetic strip inside the gong to conduct the magnetic flows from the permanent magnet to a point adjacent the ends of the plunger.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

1. An alternating current signal device comprising a gong of magnetic material, a permanent magnet, a solenoid winding mounted on a hollow magnetic core, the opposite ends of said core being spaced from said gong, a movable plunger of magnetic material extending through said core and having at least one striker end positioned to strike said gong, said device characterized by means positioning said permanent magnet adjacent said gong, the magnet having one of its poles in contact therewith, whereby the gong constitutes an extension pole of said permanent magnet, and magnetic means coupling the other pole of said permanent magnet to said solenoid core, whereby the core constitutes an extension of said other pole.

Number 2. The device according to claim 1, wherein said striker end comprises an arcuate surface, and non-magnetic means covering said surface, whereby the striker end is unattracted to the gong while the device is unenergized.

3. The device according to claim 1, wherein said movable plunger comprises a rod, bearing means, and means positioning said bearing means between said rod and said core to facilitate the movement of said rod.

4. The device according to claim 1, wherein said movable plunger comprises a rod having a pair of radial openings toward the opposite ends thereof, a reset spring having its ends positioned in said openings and adapted to act against the movement of said rod.

5. The device according to claim 1, wherein said movable plunger comprises a tubular member of magnetic material, a non-magnetic rod movably located within said tubular member, the ends of said rod adapted to strike said gong, said core extending axially beyond said winding, corresponding circumferential grooves in the extended portion of said core and in said rod and tubular member, means retaining said grooves in substantial alignment, the groove in said rod or said core being wider than the groove in said tubular member, the widths thereof defining the limit of axial travel of said rod.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Sauve Nov. 21, 1911 Harrington Nov. 1'7, 1914 Rollinson July 1, 1930 Fish July 24, 1951 FOREIGN PATENTS Country Date France Apr. 5, 1948 Number 

